paludis  Version 2.6.0
example_dep_label.cc

This example demonstrates how to handle dependency labels. It produces a summary of distfiles for all installed packages, together with a notice of whether that distfile is fetch-restricted.

See example_dep_spec.cc for specs.

/* vim: set sw=4 sts=4 et foldmethod=syntax : */
/** \file
*
* Example \ref example_dep_label.cc "example_dep_label.cc" .
*
* \ingroup g_dep_spec
*/
/** \example example_dep_label.cc
*
* This example demonstrates how to handle dependency labels. It produces a
* summary of distfiles for all installed packages, together with a notice of
* whether that distfile is fetch-restricted.
*
* See \ref example_dep_spec.cc "example_dep_spec.cc" for specs.
*/
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <cstdlib>
#include <list>
#include <map>
using namespace paludis;
using namespace examples;
using std::cout;
using std::endl;
using std::setw;
using std::left;
/* We store our results in a map from distfile name to whether it is fetch
* restricted. */
typedef std::map<std::string, bool> ResultsMap;
namespace
{
/* This visitor class is used to determine whether a label represents a
* fetch restriction. */
class IsLabelRestrictedVisitor
{
public:
bool result;
IsLabelRestrictedVisitor(const bool initial) :
result(initial)
{
}
void visit(const URIListedThenMirrorsLabel &)
{
result = false;
}
void visit(const URIListedOnlyLabel &)
{
result = false;
}
void visit(const URIMirrorsOnlyLabel &)
{
result = false;
}
void visit(const URIMirrorsThenListedLabel &)
{
result = false;
}
void visit(const URILocalMirrorsOnlyLabel &)
{
result = true;
}
void visit(const URIManualOnlyLabel &)
{
result = true;
}
};
/* This visitor class collects src_uri entries and stores the result in
* a provided map. Label statuses are handled by a stack. When we enter
* a block (an AllDepSpec or a ConditionalDepSpec), we duplicate the top item
* of the stack, since labels recurse into subblocks. When we encounter
* a label, we replace the top item of the stack. */
class DistfilesCollector
{
private:
ResultsMap & _results;
std::list<bool> _restricted;
public:
DistfilesCollector(ResultsMap & r, const bool initial) :
_results(r)
{
_restricted.push_back(initial);
}
{
/* When we encounter an AllDepSpec, duplicate the top item of
* our restricted stack, and then recurse over all of its
* children, and then restore the stack. */
_restricted.push_back(_restricted.back());
std::for_each(indirect_iterator(node.begin()), indirect_iterator(node.end()), accept_visitor(*this));
_restricted.pop_back();
}
{
/* Always recurse over a ConditionalDepSpec's children. In real world
* code, we would more likely check whether condition is met. */
_restricted.push_back(_restricted.back());
std::for_each(indirect_iterator(node.begin()), indirect_iterator(node.end()), accept_visitor(*this));
_restricted.pop_back();
}
{
/* When we encounter a FetchableURIDepSpec, store its distfile name.
* We handle 'a -> b' style specs by taking 'b' as the
* distfile name. */
_results.insert(std::make_pair(node.spec()->filename(), _restricted.back()));
}
{
/* Find out whether the label represents a fetch restriction.
* Change the top item of the stack as appropriate. Although
* a URILabelsDepSpec can contain multiple labels, only the last
* one is relevant. */
IsLabelRestrictedVisitor v(_restricted.back());
std::for_each(indirect_iterator(node.spec()->begin()), indirect_iterator(node.spec()->end()), accept_visitor(v));
_restricted.back() = v.result;
}
};
}
int main(int argc, char * argv[])
{
try
{
CommandLine::get_instance()->run(argc, argv,
"example_dep_label", "EXAMPLE_DEP_LABEL_OPTIONS", "EXAMPLE_DEP_LABEL_CMDLINE");
/* We start with an Environment, respecting the user's '--environment' choice. */
std::shared_ptr<Environment> env(EnvironmentFactory::get_instance()->create(
CommandLine::get_instance()->a_environment.argument()));
/* Fetch package IDs for all installed packages. */
std::shared_ptr<const PackageIDSequence> ids((*env)[selection::AllVersionsUnsorted(
/* Store a map from distfile name to whether it is fetch restricted. */
ResultsMap results;
/* For each ID: */
for (PackageIDSequence::ConstIterator i(ids->begin()), i_end(ids->end()) ;
i != i_end ; ++i)
{
/* If we don't have a fetches key, skip this package. All PackageID
* _key() functions can potentially return zero pointers, so checking is
* essential. */
if (! (*i)->fetches_key())
continue;
/* We need to know whether the default label for this package's src_uri
* is restricted. */
IsLabelRestrictedVisitor is_initial_label_restricted(false);
(*i)->fetches_key()->initial_label()->accept(is_initial_label_restricted);
/* Create a visitor that will collect distfiles, and do the collecting. */
DistfilesCollector collector(results, is_initial_label_restricted.result);
(*i)->fetches_key()->parse_value()->top()->accept(collector);
}
/* Display summary of results */
cout << left << setw(59) << "Distfile Name" << "| " << "Fetch Restricted?" << endl;
cout << std::string(59, '-') << "+" << std::string(18, '-') << endl;
for (ResultsMap::const_iterator r(results.begin()), r_end(results.end()) ;
r != r_end ; ++r)
cout << left << setw(59) << r->first << "| " << (r->second ? "yes" : "no") << endl;
}
catch (const Exception & e)
{
/* Paludis exceptions can provide a handy human-readable backtrace and
* an explanation message. Where possible, these should be displayed. */
cout << endl;
cout << "Unhandled exception:" << endl
<< " * " << e.backtrace("\n * ")
<< e.message() << " (" << e.what() << ")" << endl;
return EXIT_FAILURE;
}
catch (const std::exception & e)
{
cout << endl;
cout << "Unhandled exception:" << endl
<< " * " << e.what() << endl;
return EXIT_FAILURE;
}
catch (...)
{
cout << endl;
cout << "Unhandled exception:" << endl
<< " * Unknown exception type. Ouch..." << endl;
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}